Against a swirling montage of cosmic birth and destruction, and newsreel-style stills from his personal history, the celebrated inventor and futurist Ray Kurzweil sits in silhouette, contemplating death. He broods over mortality's toll in waste and pain, and the hopelessness and loss that people must experience in their last moments of life. "It's such a profoundly sad, lonely feeling that I really can't bear it," he admits.

Then, cheerfully, he adds, "So I go back to thinking about how I'm not going to die."

That opening sequence of Transcendent Man, the new documentary by director Barry Ptolemy that profiles Kurzweil and his ideas, neatly distills the sometimes jarring predictions and preoccupations of its subject. The film is about Kurzweil's belief that within just a few decades technology will allow human beings to transcend the physical and intellectual limitations of their biology. It also paints Kurzweil as a brilliant man who has personally always risen above the skepticism and misunderstanding of his doubters.

Cleverly edited and entertaining, Transcendent Man is unfortunately also too starstruck and reverent toward Kurzweil for its own good. It wants in part to be a movie about ideas, but frustratingly, it refuses to truly challenge any of those it raises—whether supportive or critical of him. Given that the film's theme is the salvation or destruction of the human race, its lack of commitment to a perspective other than innocent wonder is unsatisfying.

Kurzweil has always been propelled by powerful ideas, as the film makes clear. A recipient of the National Medal of Technology, he has been a pioneer in optical character recognition, speech recognition and other technologies, starting with his invention of a computer that composed music when he was just 17. His study of innovation in the 1980s convinced him that what he calls a "law of accelerating returns" governs progress, meaning that technology advances at an exponentially increasing rate. (The doubling of transistors on computer chips every 18 months, widely known as Moore's law, is one example of such an increase.)

Kurzweil popularized the concept of accelerating returns in his books The Age of Intelligent Machines (MIT Press, 1990) and The Age of Spiritual Machines: When Computers Exceed Human Intelligence (Viking, 1999), in which he predicted what the consequences of that rate of progress would be in the decades to come. He revisited and doubled down on that thesis in 2005 with The Singularity Is Near (Viking), a manifesto arguing that by mid-century history would reach a "technological singularity": an inflection point when artificial and enhanced intelligences would take control of further progress and usher in a kind of earthly nirvana. Genetics, nanotechnology and robotics would put immortality, infinite resources and boundless intelligence at the disposal of humanity and its sentient creations.

Dizzying as this vision can be, Transcendent Man does a good job of introducing viewers to it through well-chosen visuals and sound bites. Director Barry Ptolemy says that when he read The Singularity Is Near, he was convinced that it was one of the most profound books ever written and that he had to make a film about it. With Kurzweil's cooperation, Ptolemy spent two years following the futurist across five continents as he went about his multiple businesses and preached the creed of exponential progress.

Notwithstanding Kurzweil's certainty, many people are unpersuaded by his ideas—particularly in some of the medical and technical fields that he says will soon be transformed, and even among thinkers who respect him otherwise. As Neil Gershenfeld, director of the Center for Bits and Atoms at the Massachusetts Institute of Technology, remarks on camera, "What Ray does consistently is to take a whole bunch of steps that everybody agrees on and take principles for extrapolating that everybody agrees on and show they lead to things that nobody agrees on," because "they just seem crazy."

As seen in the film, Kurzweil's response to those who don't share his perspective on technologically enhanced transcendence, particularly on the life-extension topic, is not unkind but patronizing. He realizes, he says, that people feel "threatened" by these ideas but that they will eventually accept the incremental realizations of that progress. He never seems to credit that well-informed people might disagree or disapprove of his views for reasons that have nothing to do with their own fallibility or weakness—but rather that they might be right and he might be wrong.

Similarly, Kurzweil views his own rejection of death as the only appropriate response. People who say they have learned to accept mortality are fooling themselves, he tells the camera; society numbly glorifies death because it has surrendered to it. The possibility that Kurzweil's stubborn disdain for death might spring from neurotic denial rather than from intellectual independence is apparently absurd to him.

Indeed, Kurzweil's attitude toward the idea of his own fallibility was on display in the question-and-answer session after the New York City screening of Transcendent Man. An audience member asked him about what he had gotten wrong over the years. Kurzweil mentioned that he had recently written a 150-page review of his predictions to date and concluded that about 86 percent of them were correct. (Disclosure: having taken my own look at his predictions, I have a rather different assessment—see here, here and here.) Pressed to name something he had gotten wrong, Kurzweil mentioned that he had predicted self-piloting cars to be common by now. But he hastened to point to out Google had recently tested its own autonomous vehicles that had driven themselves over 225,000 kilometers on busy roads, which meant that such vehicles would indeed be coming, just not for a few more years.

That is Kurzweil's view of his failures in a nutshell: to him, his errors are simply predictions for which essential correctness has not yet been demonstrated.

Kurzweil's manner—undemonstrative, measured, confidently detached—can seem cold, especially when he talks so matter-of-factly about shucking off the human condition as we know it. With good reason, the filmmakers work to find the warmer, quirkier soul inside Kurzweil—and to some degree they succeed. They reveal the inventor and futurist as a loving family man who has worn a Mickey Mouse watch for 30 years and lives in a beautiful house adorned with hundreds of awards and honors, a poster of Alanis Morissette and roughly 300 cat figurines. He is someone who declared early in life that he would transform the lives of the blind and deaf with his inventions, and the warm receptions that he receives from groups with those disabilities prove he made good on that promise.

Still, at times the film may work to make Kurzweil more relatable than he is. After the New York screening an audience member asked Kurzweil why it was hurtful when people called him a "crackpot." "On what basis do you think it bothers me?" Kurzweil replied. The viewer pointed out that it happened in the film during a radio call-in show, and the camera seemed to freeze on his sad expression. "The film didn't show my actual reaction," Kurzweil said. Ptolemy, who was also on stage, did not comment.

The emotional spine of the film is Kurzweil's love for his father, a composer whose "genius was thwarted" in life, he says, and who died at 58 of heart disease. The film weds Kurzweil's refusal to accept death's inevitability to his quest for immortality, which he believes advances in medicine and technology will achieve before he himself dies. In effect, the film dares viewers to draw the pop psychology conclusion that Kurzweil's faith in techno-immortality is really a fantasy he's projected to avoid confronting his fears of death—an opinion that Kurzweil would surely dispute.

Therein lies the biggest flaw in the movie: it refuses to ask that question and challenge Kurzweil's own narrative about his beliefs. Kurzweil acknowledges that his father's death was momentous for him (and credits the film with helping him realize it), but he never concedes or even addresses on camera whether that fact might bear on his certainty that the Singularity will arrive during his lifetime.

The film is evenhanded enough to give some of Kurzweil's more respectful critics a chance to air their disagreements with him, but it never shows anyone arguing directly with Kurzweil, so viewers are left with no sense of who might have the better-reasoned perspective. The film seems dedicated to this hands-off approach. Ptolemy followed Kurzweil for two years and was clearly immersed in those ideas; surely he must have his own opinion of them. But if so, he keeps it under wraps.

The absence of a challenge in the film is sorely missed everywhere, but especially in Kurzweil's poignant, bizarre belief that technology will someday help him resurrect his father. With degraded DNA scavenged from his father's grave, memories plucked from the brains of those who knew him, and information in the man's papers and music (which Kurzweil has scrupulously warehoused), post-Singularity technology will supposedly be able to whip up a replica of the man.

It is hard to know where to begin in pointing out the problems with that plan. But technical and philosophical reservations aside, what does it say about Kurzweil's personality that he would consider such a thin simulacrum to be his father, or even an appealing proxy for him? A more incisive documentary would want to know.

Kurzweil and Transcendent Man want to evangelize that technology will help human beings rise above the limitations of their biology and become something literally more divine. Yet Kurzweil comes across as naively uninterested in the philosophical and practical implications of that possibility—not unaware of them, but blithely optimistic that the problems will work out. And paradoxically, in a film about an expansion of what it could mean to be human the protagonist sometimes seems so emotionally off-kilter that his own humanity feels unrealized.

Futurist Kevin Kelly—who is no stranger to wild technological extrapolations, as in his 2010 book What Technology Wants (Viking)—thinks that Kurzweil is probably right about where the technology is heading but far too optimistic about how soon immortality and other dreams will be realized. In the film he describes Kurzweil as "more a poet than a mechanic," and adds that Kurzweil's unswerving commitment to his ideas makes him a kind of "modern-day prophet…that's wrong."

Kelly's assessment may be the canniest of any in the film. Kurzweil is devoutly sure that the angels of exponential progress will triumph over all doubt. He intends to see nanotech-embodied intelligence expanding outward, inhabiting every speck of matter in the cosmos until the universe itself springs into consciousness. His eye is on the long game, the infinitely long game that he intends to witness personally. Those critics who join him in eternity will come to realize that he was the one who saw it first and best—a singular distinction, if you will.

"Does God exist?" Kurzweil asks rhetorically in the film. "I would say, 'Not yet.'" The wittiness of the joke almost hides the immodesty at its core.

(During February, Kurzweil and Ptolemy will be on tour with Transcendent Man, with screenings in New York City, San Jose, Los Angeles, Washington, D.C., Boston, London and Toronto, leading up to the film's release on iTunes and Movies on Demand on March 1. A DVD release is scheduled for May 24. Visit transcendentman.com for details.)